The empennage at the tail of every fixed-wing aircraft is built from two perpendicular surfaces: the horizontal stabilizer and the vertical stabilizer. Mounted horizontally on the left and right sides of the tail, the larger horizontal stabilizer, or tailplane, keeps the aircraft in longitudinal trim by generating an upward force that balances pitching moments. The vertical stabilizer, or fin, stands upright on the tail centerline and prevents the nose from yawing sideways. Together, these surfaces provide the basic stability the pilot needs to maintain steady, controllable flight without continuous control inputs.
Expert behind this article
Jim Goodrich
Jim Goodrich is a pilot, aviation expert and founder of Tsunami Air.
What is the difference between a horizontal stabilizer and a vertical stabilizer?
The horizontal stabilizer is the larger, usually fixed part of the tail. The vertical stabilizer is installed vertically on the airplane's tail and consists of a small, thin piece of material whose purpose is derived from the plane's rudder, which steers the airplane to the left and right sides. Conventional tails use both surfaces, yet some airplanes have multiple vertical stabilizers: the double layout appears in the F-15, A-10, F-35 and A300 Super Transporter.
The V-tail is a horizontal stabilizer that gives a larger horizontal projected area than the vertical one typical of conventional tails. In this pair of surfaces, two stabilizers (fins and rudders) are mounted at 90-120 degrees to each other. T-tail is a vertical stabilizer characterized by a horizontal bar on top, whereas the elevator is used to deflect the tail up and down.
What is the function of horizontal and vertical stabilizer in aircraft?
The horizontal stabilizer controls the pitch, the up-and-down motion of the nose. Its elevator is used to deflect the tail up and down, altering the angle of attack so the aircraft can fly slower without stalling. Because wings create nose-down tendency, this same surface produces a downward force that balances the nose-down tendency created by the wings, keeping the summation of pitch moments about the center of gravity at zero.
Yaw, the side-to-side motion of the nose, is managed by the vertical fin. The vertical fin provides directional stability and prevents unwanted yawing motions, while its hinged rudder allows the pilot to steer the aircraft. Some large designs, like the Antonov 225 Mriya, employ an H-tail that has two vertical fins, doubling the lateral authority without enlarging a single vertical fin.
How is the horizontal stabilizer controlled compared to the vertical stabilizer?
The horizontal stabilizer is controlled through the elevator, the surface that deflects the tail up and down and thus governs pitch movement. The pilot or the autopilot controls elevators, sending hinge commands that move the elevators on the trailing edge while the rest of the stabilizer remains fixed. On some designs, an adjustable stabilizer accomplished by jackscrew mounted on the leading edge of the stabilator allows the entire stabilator to pivot about rear spar for fine pitch trim, yet the primary pitch command still originates at the elevator. Vertical stabilizer commands are delivered by the rudder. The rudder changes the airflow around the vertical stabilizer and is used to deflect the tail to the left and right, giving yaw control. The fin stays immobile, and only the rudder itself swings, making the vertical axis simpler and lighter to operate than the horizontal.
What are the advantages of the horizontal and vertical stabilizers in an aircraft?
The advantages of the horizontal stabilizer is that it gives longitudinal balance and trim. Trimming the pitch moment keeps the summation of pitch moments about the center of gravity near zero, letting the pilot fly hands-off. Because the surface adds a slight downward force on the tail, it helps flare during landing, so touchdown speeds stay low. The vertical stabilizer brings steady yaw stability and houses the rudder, which gives the pilot authority to hold heading, counter adverse yaw, or execute controlled slips. With minor rudder inputs the pilot makes minor adjustments to yaw during takeoff, landing, and in-flight maneuvers. On aircraft like the Antonov 225 Mriya, twin vertical fins reduce hangar overhead requirement, and the H-tail arrangement lets the horizontal surface act as a pitch-control device. The pilot can use the horizontal tail surfaces to change the angle of attack, allowing the aircraft to fly slower without stalling while the vertical fins supply positive stability. Twin fins, together with wings swept backwards, increase yaw stability and reduce drag.
What are the disadvantages of the horizontal and vertical stabilizers in an aircraft?
Disadvantages of the horizontal and vertical stabilizers include that both surfaces add extra area and weight, so the vertical fin carries a weight penalty over conventional tail designs while the additional area causes complexity throughout the structure. The large profile of the vertical stabilizer tends to cause drag. On T-tail layouts the tail sits in low-energy wake at very high angle of attack, so T-tail aircraft are more susceptible to a deep stall with low airspeed and aft CG.
